Identification and Characterization of Non-Host Resistance Mechanisms Against Puccinia graminis and Puccinia coronata in Brachypodium species

Puccinia graminis, the causal agent of wheat stem rust, and Puccinia coronata, the causal agent of oat crown rust are two devastating pathogens that affect the worldwide production of small grains such wheat, barley and oat. Advancing our understanding of rust disease resistance is critical to develop strategies to prevent agronomic losses and enhance grain production. Possible strategies to facilitate durable disease resistance include the introduction of genes from closely related species into crops or genome editing based on sequence information from other plants. Brachypodium distachyon is an experimental model plant for which numerous genetic resources have been developed; the phylogenetically relatedness of the species to temperate cereals makes this system highly attractive to investigate various biological traits in monocots. Because B. distachyon demonstrates genetic resistance against several wheat rust fungi including stem rust, this species is considered a valuable resource with applications to crop improvement and translational research.  Here, we propose the amenability of Brachypodium as a model system to study crown rust and present an initial screen to identify genetic factors responsible for restricting rust infection. Furthermore, we are examining the putative roles of several Brachypodium genes in mediating pathogen recognition and defense responses against rust. We utilize a library of B. distachyon T-DNA insertional mutants in the genetic background of Bd21-3 to assess whether disruption of candidate genes have an effect in rust resistance. After implementing a screening platform to work with these mutants, we report three candidate genes likely associated in rust resistance.